a) Filed of the Invention
The present invention generally relates to shipborne facilities for an automatic identification system (AIS). More specifically, the present invention relates to an ADE unit for an AIS, i.e., an outdoor unit capable of being used as an ADE which together with BDE constitutes the shipborne facilities for the AIS.
b) Description of the Related Art
b1) Introduction
As disclosed in the Japanese Patent Laid-Open Publication Nos. H11-326511 and H11-331110, the AIS is a system aimed to contribute to safe and efficient navigation of a ship. To achieve this, the AIS serves to automatically receive/transmit radio messages including static and dynamic information between ships or between a ship and a coast station. In general, the static information contained in a message would not be changed merely by the movement of the ship that originates the message or by the elapse of time. The static information includes items of information useful for identifying the ship that originates the message, such as vessel name, IMO (International Maritime Organization) number, call sign, and so on. The static information also includes other information relating to the character and schedule of the current voyage of the ship originating the message. This information may include the likes of length, width, type, draft, destination, cargo, etc. of the ship. Unlike the static information, the dynamic information including the current position (e.g., longitude and latitude), speed of the ship changes over time and as the ship moves.
The AIS consists of coast facilities installed at coast stations and shipborne facilities mounted on individual ships. To realize ship-to-ship and ship-to-coast station automatic radio messaging, the shipborne facilities must include the following devices.
First, a circuit and an antenna for performing and controlling communications of radio messages are required.
Second, a means for providing a crew of a ship, on which the facility is installed, with static and dynamic information concerning their ship and other ships is necessary. This can be implemented by various display devices, e.g., a CRT and an LCD, and audio output devices including a speaker, a speech synthesizer, and so on.
Third, a means for setting the static information concerning the ship may be necessary. This can be implemented by independent input devices, e.g., a keyboard and a pointing device, or other input devices associated with the display device, such as an operation panel provided on or beside the screen of the display device.
Fourth, a means for obtaining the dynamic information of the ship by way of, for example, measurement may also be needed. Examples of devices used for this purpose include a wireless positioning device, which is best represented by a GPS (global positioning system) receiver, and various sensors, such as a gyrocompass, a log, or the like. Alternatively, another GNSS (global navigation satellite system) may be used in place of, or together with the GPS. The GPS or the GNSS to be used may be supported by terrestrial or satellite supplemental signals. One example is a DGPS (differential GPS) which provides a differential function using a supplemental signal. An SBAS (satellite based augmentation system), which is one type of DGPS designed to have functions of ranging, differential, and integration using satellite signals, may also be used.
b2) Shipborne Facilities
FIGS. 13 and 14 show an example arrangement of conventionally developed shipborne facilities. In the figures, the above deck equipment(ADE) consists of an antenna and its peripheral devices, while the below deck equipment (BDE) includes devices installed in the residential area or workspaces, such as the pilothouse, of the crew. In the figures, a broken line represents the conceptual border line between the ADE and the BDE. A similar line is used in FIGS. 1 and 12 which will be described later.
In the example shown in FIG. 13, the ADE includes a GPS antenna for PPS (pulse-per-second) 10a, a VHF antenna 10b, and a GPS antenna for positioning 30a. The example shown in FIG. 14 further includes a long range antenna 50a. 
In the example shown in FIG. 13, the BDE includes an AIS transponder 10, an AIS display device 20, and a GPS receiver for positioning 30. The example shown in FIG. 14 further includes a long range aiding device 50 and an associated interface 50b, and a gyrocompass 60 and an associated interface 60a. 
As can be seen, various transmission lines are provided between places where the ADE and the BDE are provided, to connect between the ADE and the BDE.
The AIS transponder 10, which belongs to the BDE, includes a VHF radio circuit 10c, a controller 10d, and a GPS receiver for PPS 10e, as shown in FIG. 15. It also has a power supply or the like which is not shown. The VHF radio circuit 10c carries out the above-mentioned messaging and consists of a TDMA transmitter 10f, a TDMA receiver 10g, a DSC receiver 10h, and other components. The TDMA transmitter 10f and the TDMA receiver 10g are circuits for receiving and transmitting the message according to the TDMA (time-division multiple-access) method. The TDMA transmitter 10f uses the VHF antenna 10b to transmit both static and dynamic information concerning the ship on which the AIS transponder 10 is installed to other ships or to coast stations. The TDMA receiver 10g uses the VHF antenna 10b to receive from other ships static and dynamic information concerning them. In addition, the DSC receiver 10h uses the VHF antenna 10b to receive DSC (digital selective calling) calls to the ship. It should be noted that, although for the sake of simplicity of drawing, each of the transmission and receiving functions is represented by a single block, additional transmission and receiving systems would be provided as needed in practice according to international law or protocol.
The controller 10d controls transmitting/receiving operations of the VHF radio circuit 10c as described below. First, when the TDMA receiver 10g installed on a first ship receives static and dynamic information concerning, e.g., of another ship, the controller 10d correspondingly causes the TDMA transmitter 10f to transmit the static and dynamic information concerning the first ship. To succeed in this messaging operation, synchronization in terms of timing of TDMA time slot must be established between the two ships. To do this, the GPS receiver for PPS 10e uses the GPS antenna 10a to receive a navigation message from a GPS satellite which is in orbit around the earth and, based on received data, derive a reference clock to generate a PPS signal. According to the PPS signal supplied from the GPS receiver for PPS 10e, the controller 10d controls the operation of the VHF radio circuit 10c to synchronize the operation of the VHF radio circuit 10c, such as the timing of the TDMA slot, with that of other ships. To secure a precise reference clock, the signal path connecting the GPS receiver for PPS 10e and the controller 10d should be as short as possible in order to suppress any delays along the signal path. In consideration of this, the receiver for PPS 10e is installed inside the AIS transponder 10.
The controller 10d receives the static and dynamic information concerning its own ship and supplies this information to the TDMA transmitter 10f to be delivered to other ships. The static information concerning the ship is set in advance in the hardware of the controller 10d, or stored therein in a nonvolatile manner. Alternatively, it may also be possible for a crewmember or some other person to set such information at a particular time before departure of the ship, by operating an operation section associated with the AIS display 20. The operation section may be formed by such devices as buttons beside the display screen, a touch panel on the screen, or an associated keyboard. Pieces of the dynamic information of the ship regarding the current position (latitude and altitude), the sailing speed of the ship, etc. can be obtained from the GPS receiver for positioning 30. The GPS receiver for positioning 30 receives a signal from a GPS satellite using the GPS antenna 30a and, based on the received information, carries out predetermined positioning operations. The information concerning the heading of the ship, which is included in the dynamic information, may be obtained from the gyrocompass 60. Various sensors and devices, including ones not described herein, can be used to acquire the dynamic information. If the GPS receiver for PPS 10e serves as the GPS receiver for positioning 30, the external GPS receiver may be eliminated.
The controller 10d displays on the screen of the AIS display 20 items of information corresponding to the static and dynamic information concerning other ships received by the TDMA receiver 10g from other ships or the like, preferably alone with static and dynamic information concerning the ship on which the AIS transponder 10 is installed. In principle, various feasible display styles include the likes of marking positions of other ships on the screen according to a two-dimensional coordinate system; displaying near the marked positions static information, such as the name of the ship, or the dynamic information, such as the heading of the ship; plotting the trail of other ships by accumulating and correlating previously obtained pieces of dynamic information; superimposing a radar image obtained from a radar device (not shown); superimposing an electronic chart for an ECDIS (Electronic Chart Display and Information System) retrieved from a storage device (not shown); displaying positional relationships between the ship and other ship, or between other ships, using auxiliary lines; and so on.
Other displaying styles have been devised, such as those disclosed in, for example, the Japanese Patent Application No. 2000-89902 filed with the Japanese Patent Office by the same applicant as the present application, and which is incorporated herein by reference. It should be noted that, although the AIS display 20 is preferably a dedicated display device, it is in principle possible to realize the AIS display 20 by conversion of, or in combination with, other display devices, including those for radar, ECDIS, a plotter, or the like. The AIS display 20 can also display the information received by the DSC receiver 10h or the long range aiding device 50. Examples of the long range aiding device 50 are communication devices for INMARSAT-C which is the service provided by the INMARSAT (International Mobile Satellite Organization), and other communication devices for data communications/positioning service operated by ORBCOMM (Orbital Communications Corp.).
b3) Problem
Although the shipborne facilities for the AIS have been reviewed and analyzed heretofore and many improvements have been proposed, problems remain.
First, the above-described shipborne facilities use cables or the like to connect between the ADE and the BDE. Depending on the size and the structure of the ship on which the facilities are to be installed, and on the positional relationship between the ADE and the BDE, the length of the cable could be such that attenuation loss can not be ignored. In particular, for example, a VHF antenna generally does not have an internal RF (radio frequency) amplifier, and this tends to cause a first problem of loss or degradation of the cable. Further, because the cables pick up noise, a second problem is that noise is more apparent appears when the cables are long (a second problem).
In the above-described shipborne facilities for the AIS, there is a third problem that multiple antennas and cables, and the associated labor and laborers for fitting out the ship, are required when introducing the shipborne facilities for the AIS, which complicates the installation. Depending on the relative positional relationships of respective antennas, interference or dead zone can occur in the transmitting/receiving output of each antenna, which is a fourth problem.
Further, in a case where the BDE devices such as the AIS transponder and the AIS display are transferred from one ship to another ship, work such as cutting the cable connection between the ADE with the BDE on the first ship, transporting to and installing on the second ship the removed BDE, and connecting the BDE with the ADE which is already installed on the second ship, is necessary. This makes it very difficult to adopt a portable, efficient, and economical usage style, such as the time sharing of a single BDE by several ships which do not sail simultaneously, which is a fifth problem. Also, there is a sixth problem in that there is increasing possibility of an error in cable connection when introducing or transferring BDE devices, because multiple cables are usually used for the connection of the ADE and the BDE.
In addition to the ADE side, the BDE side also has problems. First, multiple devices must be installed for the BDE, including the AIS transponder for communicating messages, an interface means for the crew, such as the AIS display, which provides information to the crew or is a setting means used by the crew; a positioning device, such as a GPS receiver, for acquiring dynamic information concerning the ship; and so on. Further, a large space is required in which to install these devices, and cable wiring associated with these devices also requires a large space. When introducing the shipborne facilities for the AIS to a relatively small ship having limited onboard space, the large volume requirement of the devices and cables is a seventh problem. An eighth problem is that it is bothersome to wire cables for connecting respective devices of the BDE.
It is possible to eliminate the external GPS receiver by allowing the internal GPS receiver for PPS stored in the AIS transponder to be used for positioning, especially by acquiring certification and authorization from a particular authority in charge, whereby the space to be occupied by the BDE and the associated cables can be reduced. It is also possible, in principle, to integrate the AIS transponder with the AIS display to form the BDE which is to be called an integrated AIS display transponder. This alleviates the inconvenience of laying cables in the BDE. However, such an integrated AIS display transponder results in a large volume apparatus, leading to a ninth problem of difficulty in transportation and installation.
With either multiple devices or large devices, there is a tenth problem in that it is difficult to mount the AIS facilities on a small floating device, such as a buoy. When connecting with the long range aiding device or the gyrocompass, it is necessary to also provide for each device an interface in order to compensate for different specifications. This not only enlarges and complicates the structure, but also increases the difficulty of wiring, creating an eleventh problem.
The present invention is directed to reducing loss or degradation of signals traveling through cables; to improving the anti-noise characteristic of the cables; to reducing the number of steps, cost, and space required for laying, transferring, and wiring cables and instances of erroneous wiring; to preventing occurrence of interference and dead zone among antennas; and to realizing downsizing, integration, a wider range of installable ships, and an extended facility usage.
To achieve the above objects, the present invention is based on a novel basic concept for constituting the shipborne AIS facilities. Specifically, heretofore proposed and developed shipborne AIS facilities are constituted according to a basic frame and design concept in which most of the facilities are installed as the BDE, and the BDE is the connected with the ADE through cables or the like. To solve the above-described problems attributable to such a basic frame concept, the present invention boldly abandons such a basic frame concept, which is common practice, and perhaps even xe2x80x9ccommon sensexe2x80x9d, to those who practice the art. The present invention provides an apparatus capable of being xe2x80x9can outdoor unit for the AISxe2x80x9d or xe2x80x9can ADE unit for the AISxe2x80x9d by unitizing the elements belonging to the ADE in accordance with a particular configuration. Essentially or additionally, the ADE unit for the AIS according to the present invention has characteristics as described below.
First, the ADE unit for the AIS according to the present invention is used in the AIS. The AIS is a system for automatically messaging in a wireless manner static information, such as the name of the ship, and dynamic information, such as the current position of the ship between ships or between a ship and a coast station. The ADE unit for the AIS according to the present invention forms a part of the shipborne facilities to be mounted on a ship. The ADE unit according to the present invention is externally installed on a ship to enable communication with other ships or the coast station. Here, externally installed primarily refers to being installed on an area of the ship exposed to the environment, such as a deck, but also includes semi-exposed spaces under a cover or a deckhead. In addition, the ADE unit for the AIS according to the present invention provides information to be supplied to the crew via a wired or wireless inboard transmission path to the interface means for the crew. The interface means for the crew may be a fixed or portable device.
The above deck unit for the AIS according to the present invention includes a container for storing various circuits. An antenna, such as a messaging antenna, is mounted on the surface of the container, which is, e.g., a VHF antenna, used for transmitting/receiving messages. The circuits stored in the container include i) a radio circuit for transmitting/receiving the message using the messaging antenna, and ii) a controller for regulating transmitting/receiving operations carried out by the radio circuit. The controller serves, for example, to supply information to be included in the message broadcasted to or destined for other ships or the coast station to the radio circuit, and to supply information included in the message received by the radio circuit from other ships or the coast station to the interface means for the crew through the inboard transmission path. Herein, the nature of the inboard transmission path is largely different from that under the conventional developmental idea. The conventional art requires the radio circuit and the controller to be placed on the BDE side. As such, conventionally, an inboard transmission path is provided for connecting between the antenna and the radio circuit. In contrast, according to the present invention, the elements that are conventionally included in the BDE, such as the radio circuit and the controller, are provided on the ADE side. Therefore, the inboard transmission path of the present invention serves primarily as a transmission path between the controller and the interface for the crew.
By transferring this portion of the devices or circuits, which conventionally are included in the BDE, to the ADE, the present invention allows the number of channels of the inboard transmission path between the ADE and the BDE to be decided independently of the number of antennas. In other words, even if multiple antennas are provided associated with the ADE, it is sufficient to provide only one inboard transmission path, e.g., a cable, between the ADE and the BDE (a solution to the third problem). Moreover, even if the inboard transmission path is implemented by a wired cable, it is unlikely that an erroneous connection or the like of the cable will occur during installation, transfer, or the like of the shipborne facilities, because only one cable is needed for the inboard transmission path between the ADE and the BDE (a solution to the sixth problem). This would also facilitate the adaptation of a portable, efficient, and economical usage style (a solution to the fifth problem).
According to the present invention, the circuits placed on the ADE side are stored in a single container, and an antenna, such as a messaging antenna, is mounted on the surface of the container. In the above-described conventional arrangement, the inboard transmission path between the ADE and the BDE serves as the transmission path for connecting between the antenna and the radio circuit. In the present invention, such an antenna-to-radio circuit transmission path corresponds to the transmission path for connecting the surface and the interior of the container. Therefore, the transmission path between the antenna and the radio circuit is short and is enclosed, for the most part, in the container, which minimizes the chance of generating loss or degradation and entering noise. A signal transmitted between the ADE and the BDE of the present invention is a processed signal passed through the radio circuit or the controller, such as a digital signal or a video signal carrying data, rather than a signal of a generally high frequency and a faint power, such as a signal transmitted between the antenna and the radio circuit. This suppresses noise entry, loss, and degradation of the signal in the inboard transmission path between the ADE and the BDE to a level low enough to be ignored or easily compensated for (a solution to the first and second problems).
In the present invention, only the interface means for the crew, such as a display and an audio output device, need be provided for the BDE. It is unnecessary to provide multiple devices for the BDE, or connect between such devices. This realizes advantages, such as reducing the space occupied by the BDE (and the associated means for connecting between the BDE and the ADE or other devices of the BDE), facilitating installation on a relatively small ship (a solution to the seventh problem), and eliminating the connection lines among respective devices of the BDE (a solution to the eighth problem). Further, the size of the interface means itself for the crew does not increase (a solution to the ninth problem).
The container stores a measuring device for generating the dynamic information to be transmitted, such as a GPS receiver, a gyrocompass, or a GPS gyro, in addition to the radio circuit, e.g., the VHF radio circuit, and the controller. One type of such measuring device stored in the container is a radio determination device, such as the GPS receiver or the GPS gyro, which generates the dynamic information including the position of the ship based on a navigation signal received through the ether. Since the radio determination device is stored in the container, it is also preferable to mount a positioning antenna, which is used for receiving the navigation signal, on the surface of the container. Although the gyrocompass may be used for detecting the heading of the ship, it is sometimes necessary to detect and integrate the gyrating speed of the bow based on the output of the gyrocompass. With the GPS gyro, it is sufficient to couple positioning results of a plurality of GPS receivers. It should be noted that the GPS gyro is a sensor which detects a bearing or an inclination of an object, e.g., a ship, on which the GPS gyro is mounted, based on the signal from multiple GPS receivers which are fixedly positioned relative to each other.
When it is desired to adopt the configuration wherein the messaging antenna and the positioning antenna are mounted on the surface of the container and the radio circuit, the controller, the position detector, and so on are stored in the container, an antenna complex is preferably provided, by integrating the messaging antenna and the positioning antenna. One approach is to install an antenna complex that consists of a planar antenna and a whip antenna. The planar antenna, such as a patch antenna, may be provided on the outer surface of the container as the positioning antenna. Because the planar antenna used in the GPS, for example, is susceptible to weather, dust or sea conditions, it is usually protected by a radio-permeable, nonmetallic radome. A whip antenna may be used as a messaging antenna, and is comprised of a pole-like conductor having an approximately xc2xc wavelength as a radiator. The whip antenna is arranged such that one end of the radiator extends externally through the radome and such that the radiator fits to the radome of the planar antenna. With this antenna structure, it is possible to provide multiple antenna functions by effectively using the container, especially the limited surface area of the container, to further minimize the ADE unit for the AIS.
One example of such an antenna complex suitable for implementing the present invention is disclosed in Japanese Patent Laid-Open Publication No. Hei 10-247815 by Koshio and Goto. In this publication, it is disclosed that the planar antenna is positioned relative to the whip antenna in such a manner that the planes of polarization of both antennas are arranged orthogonal to each other, in an attempt to avoid any interference. The cable connecting between the whip antenna and the radio circuit is also connected to the planar antenna so that the planar antenna and the whip antenna share a common grounded conductor. In this way, it is possible to substantially eliminate the influence of the presence of the planar antenna on the characteristic of the whip antenna, while relatively easily correcting and compensating for the influence of the presence of the whip antenna on the characteristic of the planar antenna (a solution to the fourth problem).
In some preferred embodiments of the present invention, the above-described antenna structure is used with a container of which at least part is formed by a conductor. The grounded conductor of the planar antenna is connected to the conductive part of the container to provide a grounded conductor for the whip antenna, thereby securing and enlarging the grounded surface of the whip antenna. In addition, at least one other portion of the container is formed by a thermal conductor placed in contact with or in proximity to the inner surface of the container in a manner that heat generated by a heating member (e.g., a radio circuit having an amplifier which generates heat during its operation) stored in the container is transmitted to the surrounding air via the container. This allows heat to be radiated and cooled by natural cooling in place of forced cooling, thereby simplifying the structure and realizing stable and highly reliable circuit operations.
In some preferable embodiments of the present invention, the whip antenna is connected to the radio circuit by a coaxial cable, where a coaxial connector is used for realizing a detachable connection. This arrangement increases the exchangeability of the whip antenna, which facilitates maintenance and replacement of the whip antenna and simplifies new installation and transfer procedures of the ADE unit for the AIS. The coaxial connector can be fixed primarily at a point of the planar antenna where a through hole is formed, and secondarily at a point of the radome where another through hole is formed. By attaching the coaxial connector at either point, the region where the through hole is formed in either the planar antenna or the radome (corresponding to the base part of the whip antenna herein) is mechanically forced by the coaxial connector, giving the unit an increased resistance to strong vibrations. When the coaxial connector is provided at the first point, an outer conductor of the coaxial connector may be connected to the grounded conductor of the planar antenna to secure and enlarge the grounded surface of the whip antenna.
At the second point, the coaxial connector is preferably fixed so as to seal the through hole of the radome in a watertight manner, realizing a simple watertight arrangement without packing rubber or a gasket. With the coaxial connector fixed to the second point, it is unlikely that the coaxial connector would cast a shadow on the planar antenna, compared to the coaxial connector at the first point, and it is very unlikely that the coaxial connector would obstruct the capturing or tracking of a satellite by the planar antenna. In addition, if the coaxial connector is provided at the first point, an inner diameter of the through hole to be formed in the planar antenna must be determined corresponding to an outer diameter of the coaxial connector, which forcedly increases the inner diameter of the through hole. With the coaxial connector provided at the second point, the inner diameter of the through hole can be made smaller, because it can be determined based on the outer diameter of the coaxial cable. A small inner diameter of the through hole may increase the design freedom of the planar antenna, which helps widen the frequency band available for the planar antenna.
Alternatively, in other preferable embodiments of the present invention, the whip antenna is connected to the radio circuit by the coaxial cable without using the coaxial connector, so as not to cast a shadow on the planar antenna. To realize this arrangement, the conductors of both the planar antenna and the whip antenna are arranged so that the grounded conductor of the planar antenna serves as the grounded conductor of the whip antenna, as described above. When connecting the coaxial cable extending from the radio circuit, the outer conductor of the coaxial cable from the radio circuit is connected to the grounded conductor of the planar antenna, and an inner conductor of the coaxial cable is connected to the radiator of the whip antenna. This not only abolishes the coaxial connector, but also secures the grounded surface of the whip antenna, suppresses the inner diameter of the hole in the planar antenna, and so on.
Examples of this type of arrangement include a first arrangement wherein the outer conductor of the coaxial cable is partly removed in advance for a predetermined length from a tip end of the coaxial cable, and the tip end of the inner conductor of the coaxial cable where the outer conductor is removed is connected to one end of the radiator of the whip antenna. Alternatively, in a second arrangement, the radiator of the whip antenna or any conductor connected therewith is extended toward the inside of the container via the through hole of the planar antenna, and the inner conductor of the coaxial cable is connected to the radiator of the whip antenna directly or indirectly. In these arrangements, the inner conductor of the coaxial cable partly serves as a radiator continuing from the radiator of the whip antenna. Optimally, the inner diameter of the through hole of the planar antenna can be reduced to the size of the outer diameter of the coaxial cable (when the coaxial cable penetrates through the hole) or to the size of the outer diameter of the inner conductor of the coaxial cable (when the part of the coaxial cable where the outer conductor is removed penetrates through the hole). This enlarges the scope of design freedom of the planar antenna.
In particular, the inner conductor of the coaxial cable is only present inside the container in the second arrangement when viewed from the planar antenna, so that replacement of the planar antenna is simplified. In the first arrangement, because the joint between the coaxial cable and the whip antenna exists external to the container when viewed from the planar antenna, the connection is made by a non-reversible connecting means, such as soldering. Alternatively, the inner conductor of the coaxial cable may be connected to the radiator of the whip antenna by a removable connector at the cost of casting a shadow on the planar antenna. In contrast, the connection of the second arrangement is made by placing a connector for directly or indirectly connecting between the coaxial cable and the whip antenna inside the container when viewed from the planar antenna. Therefore, soldering is not necessary, and a detachable connection can be realized without casting a shadow on the planar antenna. In the first arrangement, a part of the inner conductor is exposed near the tip end of the coaxial cable and used substantially as a part of the whip antenna. This part of the inner conductor is mechanically fragile and more likely to be cut off than other parts of the inner conductor. The second arrangement need not include such a fragile part, making unlikely any disconnection of the inner conductor leading to a disorder of the whip antenna.
In embodying the ADE unit for the AIS according to the present invention, it is possible to incorporate the wireless communication function of various long range aiding devices, such as the devices associated with the INMARSAT-C or ORBCOMM, into the container which is placed outdoors, in addition to the messaging function of, e.g., VHF and the positioning function of the GPS, gyros, the GPS gyro, or the like. Specifically, a long range antenna used for wireless communication of long range aiding signals is mounted on the surface of the container which stores the radio circuit, the controller, and so on, while the long range aiding device for communicating the long range aiding signals using the long range antenna is installed inside the container. It should be noted that installed in the container is a portion of the long range aiding device mainly related to the wireless communication, and that another portion of the device mainly related to the interface for the crew is formed by the above-described interface means for the crew or provided as a separate interface means associated therewith. The controller allows the long range aiding device to transmit some portions of the information supplied from the interface means for the crew via the inboard transmission path as the long range aiding signal, while supplying the long range aiding signal received by the long range aiding device to the interface for the crew via the inboard transmission path.
As described above in connection with FIG. 14, when the AIS transponder is newly installed on a certain ship, and it is desired to connect the AIS transponder with an existing or any simultaneously introduced long range aiding device, a device for interfacing between the devices must also be introduced. In contrast, if at least a portion of the long range aiding device mainly related to the signal communications is already incorporated in the container of the outdoor facilities as described above, it is only necessary to connect the circuits and elements in the container to the interface means for the crew, such as a general-purpose personal computer. In other words, there is no need to introduce the interface device between the transponder and the long range device, and the wiring can be simplified (a solution to the eleventh problem). When the AIS transponder is newly introduced to a ship having no long range aiding device, it is also possible to introduce the long range aiding function at a low cost by introducing the system utilizing the ADE unit according to one embodiment of the present invention.
To improve the portableness of the ADE unit for the AIS, it may be preferable to provide a connector for removably connecting the elements stored in the container with the inboard transmission path. The connector, or any connector separately provided for the power supply, may also be used for feeding power to the elements stored in the container from an external power supply. The portableness may further be improved by providing a cell or any generator means which generates power by discharging or generating operations inside, or on the surface of, the container.
The ADE unit for the AIS according to the present invention, together with the above-mentioned interface means for the crew and the wired or wireless inboard transmission path, forms a part of the shipborne facilities for the AIS. The shipborne facilities for the AIS correspond to the part of the AIS, especially the onboard part of the AIS, which is the system for assisting the voyage of ships by communicating messages concerning the names, locations, etc., of other ships received from them or a coast station and supplying it to each ship. Therefore, it is assumed that the present invention is used primarily on ships, but the present invention is not limited to this application. For example, the present invention can be implemented as a waterborne complementary unit for the AIS, such as a unit mounted on a buoy, which is mounted on a waterborne structure placed fixedly in a certain water area or a waterborne floating structure. The waterborne complementary unit for the AIS is provided with a messaging antenna on the surface of the container for wireless communications of the message. The container stores the radio circuit for automatically receiving and transmitting messages from and to ships or a coast station using the messaging antenna, and the controller for controlling the receiving/transmitting operations of the radio circuit and supplying the information to be communicated to the ships or the coast station to the radio circuit. Thus, the waterborne complementary unit for the AIS can transmit the static or dynamic information, such as the current position of the unit, concerning the waterborne structure or the waterborne floating structure on which the unit is mounted. Because the unit has a compact structure wherein one or more circuits and antennas are incorporated in a single container, the unit can more easily be mounted on, e.g., a buoy, than those arrangements shown in FIGS. 13 and 14 (a solution to the tenth problem).